What does the 'trigger' feature do on an oscilloscope?

Question

Anyone know? And what is the trigger input?
Thanks.

Answer 1

An oscilloscope makes a graph of voltage vs. time. Great. Next problem is what the origin (0,0) of the graph is.



For the vertical axis, this is a pretty easy question to answer. The 'ground' (clip) connection of the oscilloscope is the origin. If you have a differential probe or you have subtraction as a feature, you can use another signal as the reference zero. But let's not go there.



For the horizontal axis, this is a somewhat more complicated question. Time has been marching forward since the beginning of time, and it shows no sign of stopping. So how does one place the origin on the graph?



The trigger circuit of an oscilloscope declares the origin for time on the display. The simplest version of trigger 'triggers' when the input signal crosses a threshold (the 'trigger level') going a specific direction (rising edge, or falling edge).



More complex versions of trigger can look at a different signal than the signal you are graphing on the screen--external trigger. Or it can look at your wall power supply--line trigger. Fancy digital oscilloscopes have video trigger (on the start of frame or on a specific line of video), conditional trigger (connect digital inputs and trigger on a data byte), glitch trigger (trigger on a tiny pulse, but not a big one), or lots of other things.

Answer 2

Trigger Oscilloscope

Answer 3

Basically, it allows a person to stabilize the display of a signal on an oscilloscope screen.



Sometimes you need to measure signals at the channel input connector that are hard to display because their frequency is varying or are composed of multiple frequencies. The oscilloscope usually has a variable level control that might be able to synchronize it's own sweep circuitry to stabilize the channel input signal for viewing.

But if that doesn't help, then you can input a fixed frequency signal (like a sawtooth or square wave waveform) into the trigger input of the scope that will force the oscilloscope to synchronize to this signal for a stable display. However, the trigger input must be of the same frequency, or some multiple frequency, of the channel input signal that you are trying to measure.



Click on the source link I posted below for an explanation along with illustrations.

Answer 4

It's used to tell the scope when to redraw the screen.



You could connect a pushbutton and a battery to the input if you wanted. Then every time you push the button, the trace will draw.



Or, you can connect it to a function generator, and connect channel A to the output of some filter, so you can see if the filter introduces some lag.

Answer 5

it has to do with the rate at which the oscilloscope reads the signal.

it is usually connected to the input signal of your circuit.

this is done so that the graph of your output signal does not drift left and right on the screen, making it easier to read.